An explicit two-dimensional finite element model to simulate short- and long-term bed evolution in alluvial rivers

Abstract

This paper presents a two-dimensional model to solve the vertically averaged shallow water and sediment transport equations for short- and long-term simulations. The model implements a four-time-step explicit scheme that permits longer time steps than previous explicit finite element models. Also, an algorithm is incorporated that decreases considerably computer times for long-term simulations while preserving the advantages of explicit schemes. The model results compare very well with analytical solutions for simplified one- and two-dimensional problems. A 5-year simulation for the Apure River in Venezuela, demonstrate the ability of the model to predict long-term evolution for large rivers in a computational efficient manner. The resulting bed evolution patterns compare well to the observed behavior of control structures used in similar applications.